Vegetables which require peeling for end use, such as potatoes, are typically peeled in rotating drum peelers in a production line. These machines utilize an inclined drum with a fixed auger mounted to its interior which is rotated to advance potatoes at a constant rate. A series of brushes is mounted axially within the drum which rotate at a speed much greater than the drum speed. The brushes have thousands of stiff bristles which engage each potato against the drum wall and scrape a tiny portion of potato skin off with each contact with an advancing potato. Potatoes have a surface geometry which is highly irregular varying significantly from potato to potato. However, thousands of strokes by individual bristles can achieve the goal of a desired level of peel removal.
Not only do potatoes vary in size, they vary in skin adhesion, toughness, moisture content, and in other attributes which affect the ease or difficulty in removing peel. Furthermore, although these attributes vary from potato to potato, the change is more pronounced between potatoes from different producers, different harvest dates, or even loads from different fields or portions of fields. Potato product producers have strict needs for levels of peel removal in their finished product. The amount of peel on a processed potato may affect taste, cooking properties and appearance; hence, a potato peeler must remove peel at the desired level or the output will be unacceptable.
The amount of peel removed by a rotating drum peeler is a function of the number of bristle engagements with a particular potato. The number of engagements may be increased by rotating the brushes more rapidly, or by reducing the auger speed to increase the time a potato resides within the apparatus. Increased peel removal is not, however, achieved without some cost. After the first bristle has removed portions of potato peel, subsequent bristle engagements at the same location will remove not peel but usable flesh portions of the potato. Hence, excessive bristle engagements will unnecessarily reduce the amount of final processed potatoes produced, resulting in thousands of pounds of lost potatoes in a year, with a commensurate loss in revenues.
To avoid excessive peel, the brush rate should be adjusted frequently by the peeler operator. However, this adjustment requires careful attention by the machine operator, as well as a keen eye for determining levels of peel which may only vary by 2 to 12 percent.
What is needed is a vegetable peeler with an operator aid which will display peel fraction in a standardized format to the operator to allow vegetables to be peeled to a desired level and which will be self-adjusting under operator supervision to accommodate variations in input vegetable attributes.